The invention relates to a mechanical-optoelectronic angle comparator for determination of the angular position of a weapon mounted on a combat vehicle relative to the line of sight. Determination of that angular position with a high degree of accuracy is of importance especially when the line of sight is primarily stabilized, as is the case with modern fighting tanks, and the weapon is made to track the line of sight, in other words, when the position of the axis of rotation of the objective mirror of the sighting device is not mechanically coupled directly to the position of the weapon.
It is known to determine and compare the angular positions of the weapon and of the line of sight in combat vehicles by purely mechanical means, such as linkages, appropriate disk cams being provided between the linkages for control of the ballistic angle of elevation.
It is further known to determine and compare the angular positions of the weapon and of the sight in modern combat vehicles by means of synchro systems and to add the angles of elevation by analog techniques. The associated computers usually operate on an analog basis. However, it has also become known to convert the analog signals of the synchro systems for digital processing in computers.
The drawbacks of the arrangements mentioned, which are purely mechanical, is that wear and distortion due to thermal stresses result in inaccuracies which adversely affect the accuracy of fire. Especially in firing from a fast-moving vehicle, the purely mechanical systems are susceptible to vibrations which render aiming difficult or even impossible.
While the mentioned electronic systems incorporating synchros are less subject to vibrations and wear, analog signal processing in practice entails considerable difficulties since the voltage differences associated with the angle differences are in the microvolt region. In addition, the synchros must be mounted on the axis of rotation of the weapon, which is exposed to considerable mechanical stresses. Besides, this mounting location is not readily accessible.
The known arrangements are unsatisfactory also with respect to the measuring method since they measure the absolute angular position of the weapon rather than its angular position relative to the line of sight. Yet only the relative angle difference between weapon and line of sight is of significance in the use of the weapon system. The formation of the difference angle which the known arrangements thus require is apt to introduce additional errors.
Further inaccuracies, which often are additive, are due to the cable connections required with fire-control systems, environmental influences, and other interfering factors.
Besides, the known systems are complex and vulnerable to interfering electromagnetic fields. An enemy might conceivably take advantage of this weakness of fire-control systems by employing special directional-radio jamming techniques.